oscillate

Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

intransitive v. To swing back and forth with a steady, uninterrupted rhythm.

intransitive v. To waver, as between conflicting opinions or courses of action; vacillate: "The court has oscillated over the decades from more liberal to less, more conservative to less, depending upon who was president at the time of vacancies” ( Gordon J. Humphrey). See Synonyms at swing.

intransitive v. Physics To vary between alternate extremes, usually within a definable period of time.

from Wiktionary, Creative Commons Attribution/Share-Alike License

v. To swing back and forth, especially if with a regular rhythm.

v. To vacillate between conflicting opinions, etc.

v. To vary above and below a mean value.

from the GNU version of the Collaborative International Dictionary of English

intransitive v. To move backward and forward; to vibrate like a pendulum; to swing; to sway.

intransitive v. To vary or fluctuate between fixed limits; to act or move in a fickle or fluctuating manner; to change repeatedly, back and forth.

from The Century Dictionary and Cyclopedia

To swing; move backward and forward; vibrate, as a pendulum.

Hence To vary or fluctuate; waver.

Synonyms Vacillate, Waver, etc. See fluctuate.

To cause to swing or move backward and forward; cause to vibrate or swing to and fro.

Etymologies

(American Heritage® Dictionary of the English Language, Fourth Edition)

From Latin oscillatus perfect passive particple of Latin oscillō ("swing"), from oscillum ("a swing"), usually identified with oscillum ("a little face or mask hung to a tree and swaying with the wind"), diminutive of os ("mouth, face"). (Wiktionary)

Examples

She was, however, uneasy when she heard the strange whistling sound produced by their irregular passage through the dark night air, and when the violence of their movements made the basin oscillate, she lay down tremblingly at the bottom of her golden basin, and then carefully gathered her garments around her, lest they should come in contact with the dark man.